When manoeuvring aircraft on the ground for example moving aircraft in and between cargo and passenger loading and unloading bays, maintenance bays and parking and refuelling areas it is usual to move the aircraft with an aircraft ground handling tractor. Such tractors are connected to the nosewheel assembly of the aircraft by a rigid tow-bar and the tractor can then push or pull the aircraft to manoeuvre it into its required location.
As the size of aircraft has increased so the size of tow-bar and the size and power of the tractor has increased. Nowadays most tow-bars include a pair of wheels connected to the tow-bar through a hydraulic jack assembly so that, when not connected to an aircraft the tow-bar can be towed on its wheels by the ground handling tractor. Upon being manoeuvred into position adjacent the nosewheel assembly of the aircraft the hydraulic jacking mechanism is then operated to raise the free end of the tow-bar to the correct height to enable a connector located at its free end to be connected to the nosewheel assembly of the aircraft. Once it has been connected the hydraulic jack is then operated to lift the wheels of the tow-bar off the ground so that the tow-bar is supported between the ground handling tractor and the nosewheel assembly of the aircraft.
The connection between the tow-bar and the nosewheel assembly of the aircraft are often different from one aircraft type to another and, whilst some attempts have been made to standardise the nature of the connector it is often located at a different height above the ground for each aircraft type. Accordingly, even where the connectors at the end of the tow-bar can be used for more than one type of aircraft the height to which the free end of the tow-bar has to be lifted varies between aircraft of different type. Accordingly, most airports have a wide range of tow-bars and, whilst in general, all of the tow-bars can be used with any of the ground handling tractors, individual tow-bars are used exclusively with aircraft of a particular type.
DE-A-3302771 describes a proposal for an aircraft ground handling tractor which includes a manoeuvrable boom mounted on it, the free end of the manoeuvrable boom having a connector capable of being connected to an aircraft nosewheel assembly so that the tractor can be connected to the nosewheel assembly through the boom to enable it to pull or push the aircraft.